speaker specs?

[subdude]

the speaker i use currently is a PA floor monitor, it is ok but not great and with 57 pounds it is terribly heavy.
so i am thinking of building a 2x10 cab using locally available speakers. i live in kenya and none of the speakers i have sourced here are of a brand that i recognise but some of them have T&S parameters on the spec sheet. my question is, what can i learn from these parameters in order to pick the best option?

thanks for any help

[Mr. Foxen]

First you need to figure this program: http://www.linearteam.dk/default.aspx?pageid=winisdpro

It is a speaker cabinet simulator, you'll need to model some cabinets you know and like the sound of, and then model the speakers you have available and figure what is a suitable box by tweaking until the graphs come out about the same. It is useful from 200hz and below, for how the midrange 'looks' you need the graph that should come with the speaker. If you search 'WinISD' on here, there'll be a bunch of threads listing it. Some idea of the sound you are looking for will help, as well as listing the speakers that are possibles for yo, and the amp you use.

[Musky]

Start here - http://www.eminence.com/support/understanding-loudspeaker-data/- and then work your way through this lot - http://techtalk.parts-express.com/showthread.php?t=219617

Go for a speaker with an xmax above 4mm.

WinISD will take a lot of the legwork out of the design.

[Mr. Foxen]

Xmax requirement is bit dependent on the amount of power he is planning on using. Other stuff might be more important. The limited choice of locally available speakers is pretty key to this.

[melando]

It is worth checking that the drivers available to you are designed for bass guitar use, as distinct from PA, or indeed guitar. It is not always obvious from the spec sheet.

Then make sure you're comparing drivers of the right impedance - I assume you'll be using two 8 ohms units in parallel to make a 4 ohm system, although you might want to think about this - if you plan to add extra cabinets later or your amplifier has limitations in terms of the impedance it can drive.

Then consider whether you will make a closed box or ported cabinet - drivers suitable for one will generally not be ideal for another. A driver with a qts of less than about 0.45 will generally be optimised for use in a ported cabinet, above 0.45 for a closed cabinet. Drivers for use in a closed cabinet will also generally need a higher xmax due to the increased cone excursion.

Check also the the drivers have a high enough power handling for the use they're going to get.

Good luck.

[Phil Starr]

I don't know if this will help, [url="http://www.ultimate-guitar.com/columns/gear_maintenance/choosing_speakers_to_drive_your_cabs.html"]http://www.ultimate-guitar.com/columns/gear_maintenance/choosing_speakers_to_drive_your_cabs.html[/url] I tried to write something to help with this. The Eminence website stuff is useful too. Using WinISD will mean you can see what the bass response is like without having to buy and build the speakers first but it could be confusing if you don't understand the models it uses. If you can get hold of the Loudspeaker Design Cookbook by Vance Dickerson that will help but there is loads on the internet. If you ask specific questions here there are loads of bright people here who will try and help.

Good luck

[subdude]

thank you all for your help.

i use a v-amp pro as my preamp plugged into a digital PA amp. i want a clean sound and i won't need super shake down the walls volume.

as far as the available speakers go, there is almost nothing" known" available here, i found the odd 15"eminence driver but most of it is just generic stuff made in china. and also a lot of it seems to be car HI FI by the brand names (alpine, pioneer, sony etc)

here is a speaker i could buy locally that comes with some T&S parameters:

Nominal Impedance : 8 ohm
Minimum Frequency Response : 71 Hz
Reproduction Frequency Response : FS-5.8 kHz
Sensitivity / S.P.L. : 94 dB±2 dB
Power RMS : 300 W
max. Power : 500 W
Equivalent Diaphram Radius : 1.5"
Diaphram Mass inc. Airload (Mms) : 81 grams
Magnet Weight : 40 oz
Resonant Frequency (fs) : 67 Hz
DC Resistance (Re) : 5.6 ohm
Total Q (Qts) : 0.34
Mechanical Q (Qms) : 5.6
Electromagnetic Q (Qes) : 0.36
Maximum Linear Excursion (Xmax) : +/- 6 mm
Compliance Equivalent Volume (Vas) : 72 liters

it is one of the few that have some specs available, most have only the impedance and wattage printed on the magnet.
could this speaker work for my needs, the cost per piece is around 54US$

i most appreciate your comments, thanks a lot for your time.

[melando]

What size unit is the data for? The moving mass and Vas are a bit high for a 10". Is it a 15"?

[subdude]

[quote name='melando' timestamp='1331644491' post='1576406']
What size unit is the data for? The moving mass and Vas are a bit high for a 10". Is it a 15"?
[/quote]

it is a 10" speaker

[mrtcat]

If you want to learn lots about speakers and cab building you could do a lot worse than spend some time here [url="http://billfitzmaurice.info/forum/"]http://billfitzmaurice.info/forum/[/url]

I will warn you though - it will change your perception of most big brand kit.

[melando]

[quote name='subdude' timestamp='1331662312' post='1576829']
it is a 10" speaker
[/quote]

In that case, it looks like a PA type bass/midrange unit designed more for a flat response. It would probably work ok but it is likely to sound a bit dull and maybe a bit slow. Along with the high moving mass the sensitivity is a little low but if you're not after huge output levels that shouldn't be a problem. The suspension is probably a bit more compliant than that of a bass guitar driver so you need to be careful about thumping it too hard with low bass notes. It looks suited to a ported box of of around 30-40Litres per driver with the box tuned to around 65-70Hz (or lower depending on the cone excursion).

So, not ideal, but should work ok if you don't go crazy with it.

As well as the Eminence site, there are useful driver datasheets on the Celestion website.

[Phil Starr]

There's something slightly odd about the specs here. That really is quite a heavy cone and likely to be quite stiff as a result so you would expect the frequency range to be more restricted than 5.8k. You'd also expect fs to be lower.

I don't think efficiency is particularly low, we don't know how it was measured and a lot of the higher figures other manufacturers publish are generated by 'favourable' testing procedures. (It may be OK, we just don't know.) A lot of Eminence figures are bumped up by quite big mid-range frequency humps for example. You'll get an extra 6dB by having a 2x10 and 100dB per watt is good. On the plus side excursion (Xmax) looks good and Q of 0.34 is pretty near perfect for engineering a flat response in the bottom octaves without too sharp a roll off.

I quite like using PA drivers in bass cabs as I prefer the more 'polite' sound you get. You aren't happy with your current PA monitor though so maybe your taste is for something less accurate but more lively sounding. The big problem with building your own is that you can't test the sound until after you have built.

[subdude]

[quote name='Phil Starr' timestamp='1331712257' post='1577403']
There's something slightly odd about the specs here. That really is quite a heavy cone and likely to be quite stiff as a result so you would expect the frequency range to be more restricted than 5.8k. You'd also expect fs to be lower.

I don't think efficiency is particularly low, we don't know how it was measured and a lot of the higher figures other manufacturers publish are generated by 'favourable' testing procedures. (It may be OK, we just don't know.) A lot of Eminence figures are bumped up by quite big mid-range frequency humps for example. You'll get an extra 6dB by having a 2x10 and 100dB per watt is good. On the plus side excursion (Xmax) looks good and Q of 0.34 is pretty near perfect for engineering a flat response in the bottom octaves without too sharp a roll off.

I quite like using PA drivers in bass cabs as I prefer the more 'polite' sound you get. You aren't happy with your current PA monitor though so maybe your taste is for something less accurate but more lively sounding. The big problem with building your own is that you can't test the sound until after you have built.
[/quote]

melando & phil, thanks a lot for your input.
i have a few other speakers available but none of those come with any specs safe impedance and watt. i think this speaker is the best shot i have and i might just go for it.
any suggestions as to what i look for in a tweeter?